The recently introduced commit-graph auxiliary data is incompatible
with mechanisms such as replace & grafts that "breaks" immutable
nature of the object reference relationship. Disable optimizations
based on its use (and updating existing commit-graph) when these
incompatible features are in use in the repository.
* ds/commit-graph-with-grafts:
commit-graph: close_commit_graph before shallow walk
commit-graph: not compatible with uninitialized repo
commit-graph: not compatible with grafts
commit-graph: not compatible with replace objects
test-repository: properly init repo
commit-graph: update design document
refs.c: upgrade for_each_replace_ref to be a each_repo_ref_fn callback
refs.c: migrate internal ref iteration to pass thru repository argument